I am trying to enter the TXT record for MailGun in the Linode DNS Manager. v=spf1 include:mailgun.org ~all needs to be added as a TXT record in the zone I setup as mg.mydomain.com. The hostname for the record needs to be set as mg.mydomain.com. The interface will not allow me to set the hostname as mg.mydomain.com.
I tried entering @ as the host,but it would not accept that either.
Not a solution to the original question, but a solution. I signed up for gsuite and bypassed mailgun's validation system.